Given an element of the image, return an element of the codomain that maps onto it.

Note that lift and preimage_representative are
equivalent names for this method, with the latter suggesting
that the return value is a coset representative of the domain
modulo the kernel of the morphism.

Given an element of the image, return an element of the codomain that maps onto it.

Note that lift and preimage_representative are
equivalent names for this method, with the latter suggesting
that the return value is a coset representative of the domain
modulo the kernel of the morphism.